Run n-cpu using LXD_GROUP when LXD virt driver

Enabling nova-lxd require to run n-cpu using lxd group

Change-Id: I0553dafcc797fcc1342501a558c7455261cf3daf
diff --git a/lib/nova b/lib/nova
index 67a80b9..8fe4c29 100644
--- a/lib/nova
+++ b/lib/nova
@@ -825,6 +825,8 @@
         # ``sg`` is used in run_process to execute nova-compute as a member of the
         # **$LIBVIRT_GROUP** group.
         run_process n-cpu "$NOVA_BIN_DIR/nova-compute --config-file $compute_cell_conf" $LIBVIRT_GROUP
+    elif [[ "$VIRT_DRIVER" = 'lxd' ]]; then
+        run_process n-cpu "$NOVA_BIN_DIR/nova-compute --config-file $compute_cell_conf" $LXD_GROUP
     elif [[ "$VIRT_DRIVER" = 'fake' ]]; then
         local i
         for i in `seq 1 $NUMBER_FAKE_NOVA_COMPUTE`; do